Choose diet or zero-sugar cola for its taste and caffeine status, not to replace carbohydrate fuel during a long run: Coca-Cola GB and PepsiCo UK list 0g carbohydrate per 100ml for standard Diet Coke, Coca-Cola Zero Sugar and Pepsi Max. A caffeine-free version suits someone who wants to avoid caffeine, but fluid replacement and carbohydrate intake remain separate decisions.
If you want to keep drinking cola during training, the important distinction is between a drink you enjoy and the carbohydrate you plan to take on a long run. A zero-sugar cola does not replace a gel, carbohydrate drink or carbohydrate-containing food.
Standard diet and zero-sugar colas can contain caffeine, while named caffeine-free variants offer a different choice. Check the exact version if caffeine timing or your response to it matters to you.
An own-label diet cola may suit an everyday taste preference. Read its own nutrition and ingredient labels rather than assuming it has the same carbohydrate content or caffeine status as a branded product.
Plan carbohydrate and fluids for the run first; then decide whether the cola you prefer should contain caffeine.
| Priority | What to check | Your needs |
|---|---|---|
| Carbohydrate | Read the value per 100ml on the exact pack. Coca-Cola GB lists 0g carbohydrate per 100ml for standard Diet Coke and Coca-Cola Zero Sugar; PepsiCo UK lists 0g for Pepsi Max. Consider carbohydrate for a prolonged run separately from your cola choice. | I enjoy cola, but need to arrange running fuel separately if the session calls for carbohydrate. |
| Caffeine | Check whether the variant contains caffeine. Standard Diet Coke, Coca-Cola Zero Sugar and Pepsi Max list it; Diet Coke No Caffeine and Pepsi Max No Caffeine are named alternatives. If choosing caffeine, try the timing during ordinary training rather than for the first time on race day. | For a later drink, or if I prefer to avoid caffeine, I would choose a caffeine-free variant rather than assume all diet colas are alike. |
| Fluids | Decide how you will replace fluids independently of how you will obtain carbohydrate. The NHS identifies water as the way to replace fluids lost through physical activity; a zero-carbohydrate cola does not meet a carbohydrate-fuelling need just because it is a drink. | I want a drink I like without confusing it with my plan for fluids and fuel during a sweaty long run. |
| Exact label | Check the current pack for carbohydrate, sugars, caffeine and sweeteners, especially when switching brands or variants. Coca-Cola GB labels Coca-Cola Zero Sugar as containing a source of phenylalanine. | Ingredients or label statements may matter to me, so I would check the particular cola I am buying. |
Coca-Cola GB and PepsiCo UK list 0g carbohydrate per 100ml for standard Coca-Cola Zero Sugar, Diet Coke and Pepsi Max. Drinking one instead of planned carbohydrate would leave that fuelling need unmet.
Work out how you will obtain carbohydrate and fluids for the session, then choose a diet cola for taste and caffeine preference.
The Journal of the International Society of Sports Nutrition’s 2021 position stand describes variation in people’s responses to caffeine, including possible effects on sleep and feelings of anxiety.
If you choose a caffeinated cola, try your preferred amount and timing in routine training. Choose a caffeine-free version if you do not want caffeine.
PepsiCo UK lists 15g carbohydrate in a 330ml can of regular Pepsi. That distinguishes it from Pepsi Max, but the carbohydrate in one can does not, by itself, settle your fluid and fuelling plan.
Consider the whole run plan and practise the food and drinks you intend to use, rather than relying on a cola can alone.
These brand references help distinguish named drinks and variants; check the exact product label before buying.
Diet Coke and Coca-Cola Zero Sugar are relevant when choosing between standard and caffeine-free cola variants.
Pepsi Max and Pepsi Max No Caffeine offer different caffeine choices; regular Pepsi has a different carbohydrate content.
Tesco Caffeine Free Diet Cola is an own-label option for someone who wants cola without caffeine.
Sainsbury's Diet Cola is an own-label option for shoppers comparing diet-cola labels.
These Joybuy multipacks offer caffeinated and caffeine-free diet or zero-sugar cola choices. They are options for drinking alongside a separate marathon-training fuel and fluid plan.
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Choose this variant if you want a diet cola without caffeine alongside, rather than instead of, your running-fuel plan. The pack contains 24 × 330ml cans; check the current label for carbohydrate and ingredient details that matter to you.
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This is a caffeinated diet-cola choice, not a replacement for carbohydrate fuel. The pack contains 24 × 330ml cans; Coca-Cola GB lists 0g carbohydrate per 100ml for standard Diet Coke. Consider caffeine timing and check the current pack label.
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Choose this if you prefer Pepsi Max without caffeine while keeping running fuel separate. The pack contains 24 × 330ml cans; PepsiCo UK lists less than 0.1g carbohydrate per 100ml for Pepsi Max No Caffeine, so it is not a carbohydrate-fuelling drink.
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This caffeinated zero-sugar cola is a drink preference, not a source of running carbohydrate. The pack contains 24 × 330ml cans; PepsiCo UK lists 0g carbohydrate per 100ml for Pepsi Max. Check the pack if caffeine timing or ingredients matter to you.
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This is a caffeinated zero-sugar cola to consider alongside a separate fuel and fluid plan. The pack contains 24 × 330ml cans; Coca-Cola GB lists 0g carbohydrate per 100ml and labels the drink as containing a source of phenylalanine. Check the current pack if that statement matters to you.
Not as a carbohydrate source. Coca-Cola GB and PepsiCo UK list 0g carbohydrate per 100ml for those standard products, so arrange carbohydrate for a prolonged run separately if your plan calls for it.
Choose one when you want cola without caffeine. Diet Coke No Caffeine and Pepsi Max No Caffeine are named alternatives to their caffeinated versions, but avoiding caffeine does not turn either drink into running fuel.
Do not assume it does. PepsiCo UK lists 15g carbohydrate per 330ml can of regular Pepsi, unlike Pepsi Max, but you still need to consider carbohydrate and fluids across the whole run rather than judging a plan by one can.
The NHS identifies water as the way to replace fluids lost through physical activity. Treat that fluid decision separately from whether you need food or a drink containing carbohydrate after the run; diet cola alone does not supply meaningful carbohydrate.
Check carbohydrate and sugars per 100ml, caffeine, sweeteners and any ingredient statements on the exact variant. For example, Coca-Cola GB labels Coca-Cola Zero Sugar as containing a source of phenylalanine; do not assume another cola has an identical ingredient list.